EN 62341-6-2:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Anzeigen mit organischen Leuchtdioden (OLEDs) - Teil 6-2: Messverfahren für Bildqualität und UmgebungsbetriebseigenschaftenAfficheurs à diodes électroluminescentes organiques (OLED) - Partie 6-2: Méthodes de mesure de la qualité visuelle et des caractéristiques de fonctionnement sous conditions ambiantesOrganic light emitting diode (OLED) displays - Part 6-2: Measuring methods of visual quality and ambient performance31.120Elektronske prikazovalne napraveElectronic display devicesICS:Ta slovenski standard je istoveten z:EN 62341-6-2:2012SIST EN 62341-6-2:2012en01-junij-2012SIST EN 62341-6-2:2012SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 62341-6-2 NORME EUROPÉENNE
EUROPÄISCHE NORM March 2012
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2012 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62341-6-2:2012 E
ICS 31.260
English version
Organic light emitting diode (OLED) displays -
Part 6-2: Measuring methods of visual quality and ambient performance (IEC 62341-6-2:2012)
Afficheurs à diodes électroluminescentes organiques (OLED) -
Partie 6-2: Méthodes de mesure de la qualité visuelle et des caractéristiques de fonctionnement sous conditions ambiantes (CEI 62341-6-2:2012)
Anzeigen mit organischen Leuchtdioden (OLEDs) -
Teil 6-2: Messverfahren für Bildqualität und Umgebungsbetriebseigenschaften (IEC 62341-6-2:2012)
This European Standard was approved by CENELEC on 2012-02-28. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Foreword The text of document 110/338/FDIS, future edition 1 of IEC 62341-6-2, prepared by IEC TC 110, "Flat panel display devices" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62341-6-2:2012.
The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2012-11-28 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2015-02-28
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.
Endorsement notice The text of the International Standard IEC 62341-6-2:2012 was approved by CENELEC as a European Standard without any modification. SIST EN 62341-6-2:2012

- 3 - EN 62341-6-2:2012
Annex ZA (normative)
Normative references to international publications with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050 Series International electrotechnical vocabulary
- -
IEC 60081 - Double-capped fluorescent lamps - Performance specifications EN 60081
-
IEC 61966-2-1 - Multimedia systems and equipment - Colour measurement and management -
Part 2-1: Colour management - Default RGB colour space - sRGB EN 61966-2-1 -
IEC 62341-1-2 - Organic light emitting diode displays -
Part 1-2: Terminology and letter symbols EN 62341-1-2 -
CIE 15 2004 Colorimetry - -
IEC 62341-6-2 Edition 1.0 2012-01 INTERNATIONAL STANDARD NORME INTERNATIONALE Organic light emitting diode (OLED) displays –
Part 6-2: Measuring methods of visual quality and ambient performance
Afficheurs à diodes électroluminescentes organiques (OLED) –
Partie 6-2: Méthodes de mesure de la qualité visuelle et des caractéristiques de fonctionnement sous conditions ambiantes
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE X ICS 31.260 PRICE CODE CODE PRIX ISBN 978-2-88912-893-8
– 2 – 62341-6-2 © IEC:2012 CONTENTS FOREWORD . 4 1 Scope . 6 2 Normative references . 6 3 Terms, definitions and abbreviations . 6 3.1 Terms and definitions . 6 3.2 Abbreviations . 9 4 Structure of measuring equipment . 9 5 Standard measuring conditions . 9 5.1 Standard measuring environmental conditions . 9 5.2 Standard lighting conditions . 10 5.2.1 Dark-room conditions . 10 5.2.2 Ambient illumination conditions . 10 5.3 Standard setup conditions . 15 5.3.1 General . 15 5.3.2 Adjustment of OLED display modules . 15 5.3.3 Starting conditions of measurements . 16 5.3.4 Conditions of measuring equipment . 16 6 Visual inspection of static images . 17 6.1 General . 17 6.2 Classification of visible defects . 17 6.2.1 Classification scheme . 17 6.2.2 Reference examples for subpixel defects . 17 6.2.3 Reference example for line defects . 19 6.2.4 Reference example for mura defects . 19 6.3 Visual inspection method and criteria . 20 6.3.1 Standard inspection conditions . 20 6.3.2 Standard inspection method . 21 6.3.3 Inspection criteria . 23 7 Electro-optical measuring methods under ambient illumination . 24 7.1 Reflection measurements . 24 7.1.1 Purpose . 24 7.1.2 Measuring conditions . 24 7.1.3 Measuring the hemispherical diffuse reflectance factor . 25 7.1.4 Measuring the reflectance factor for a directed light source . 27 7.2 Ambient contrast ratio . 29 7.2.1 Purpose . 29 7.2.2 Measuring conditions . 29 7.2.3 Measuring method . 30 7.3 Ambient display colour . 30 7.3.1 Purpose . 30 7.3.2 Measuring conditions . 30 7.3.3 Measuring method . 30 7.4 Ambient colour gamut volume . 31 7.4.1 Purpose . 31 7.4.2 Measuring conditions . 32 7.4.3 Measuring method . 32 SIST EN 62341-6-2:2012

62341-6-2 © IEC:2012 – 3 – 7.4.4 Reporting . 33 Annex A (informative)
Measuring relative photoluminescence
contribution from displays . 35 Annex B (informative)
Calculation method of ambient colour gamut volume . 38 Bibliography . 44
Figure 1 – Example of visual inspection room setup
for control of ambient room lighting and reflections . 10 Figure 2 – Example of measurement geometries for diffuse illumination condition
using an integrating sphere and sampling sphere . 13 Figure 3 – Directional source measurement geometry using an isolated source . 15 Figure 4 – Directional source measurement geometry using a ring light source . 15 Figure 5 – Layout diagram of measurement set up . 16 Figure 6 – Classification of visible defects . 17 Figure 7 – Bright subpixel defects . 18 Figure 8 – Criteria for classifying bright and dark subpixel defects . 19 Figure 9 – Bright and dark line defects . 19 Figure 10 – Sample image of line mura defect associated with TFT non-uniformity . 20 Figure 11 – Example of spot mura defect in a grey background . 20 Figure 12 – Setup condition for visual inspection of electro-optical visual defects . 22 Figure 13 – Shape of scratch and dent defect . 24 Figure 14 – An example of range in colours produced by a given display
as represented by the CIELAB colour space . 33 Figure A.1 – Scaled bi-spectral photoluminescence response from a display . 36 Figure A.2 – Decomposed bi-spectral photoluminescence response from a display . 36 Figure B.1 – Analysis flow chart for calculating the colour gamut volume . 38 Figure B.2 – Graphical representation of the colour
gamut volume for sRGB in the CIELAB colour space . 39
Table 1 – Definitions for type of scratch and dent defects . 24 Table 2 – Eigenvalues M1 and M2 for CIE Daylight Illuminants D50 and D75 . 26 Table 3 – Example of minimum colours required for
gamut volume calculation of a 3-primary 8-bit display . 32 Table 4 – Measured tristimulus values for the minimum set of colours
(see Table 3) required for gamut volume calculation under the
specified ambient illumination condition . 34 Table 5 – Calculated white point in the darkened room and ambient condition . 34 Table 6 – Colour gamut volume in the CIELAB colour space . 34 Table B.1 – Tristimulus values of the sRGB primary colours . 39 Table B.2 – Example of sRGB colour set represented in the CIELAB colour space . 39 Table B.3 – Example of sRGB colour gamut volume in the CIELAB colour space . 40
– 4 – 62341-6-2 © IEC:2012 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –
Part 6-2: Measuring methods of visual quality and ambient performance
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62341-6-2 has been prepared by IEC technical committee 110: Electronic display devices. The text of this standard is based on the following documents: FDIS Report on voting 110/338/FDIS 110/353/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of the IEC 62341 series, published under the general title Organic light emitting diode (OLED) displays, can be found on the IEC website. SIST EN 62341-6-2:2012

62341-6-2 © IEC:2012 – 5 – The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be • reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer.
– 6 – 62341-6-2 © IEC:2012 ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –
Part 6-2: Measuring methods of visual quality and ambient performance
1 Scope This part of IEC 62341 specifies the standard measurement conditions and measurement methods for determining the visual quality and ambient performance of organic light-emitting diode (OLED) display modules and panels. This document mainly applies to colour display modules.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050 (all parts), International Electrotechnical Vocabulary
(available at ) IEC 60081, Double-capped fluorescent lamps – Performance specifications IEC 61966-2-1, Multimedia systems and equipment – Colour measurement and management – Part 2-1: Colour management – Default RGB colour space – sRGB IEC 62341-1-2, Organic light emitting diode displays – Part 1-2: Terminology and letter symbols
CIE 15:2004, Colorimetry 3 Terms, definitions and abbreviations For the purposes of this document, the terms, definitions and abbreviations given in IEC 62341-1-2 and IEC 60050-845:1987 as well as the following apply. 3.1 Terms and definitions 3.1.1
visual inspection a means for checking image quality by human visual observation for classification and comparison against limit sample criteria 3.1.2
subpixel defect
for colour displays, all or part of a single subpixel, the minimum colour element, which is visibly brighter or darker than surrounding subpixels of the same colour. They are classified depending on the number and configuration of multiple subpixel defects within a region of the display
62341-6-2 © IEC:2012 – 7 – 3.1.3
dot defect for monochromatic displays, all or part of a single subpixel, the minimum dot element, which is visibly brighter or darker than surrounding dots. They are classified depending on the number and configuration of multiple subpixel defects within a region of the display 3.1.4
bright subpixel defect subpixels or dots which are visibly brighter than surrounding subpixels of the same colour when addressed with a uniform dark or grey background 3.1.5
dark subpixel defect
subpixels or dots are visibly darker than surrounding subpixels of the same colour when addressed with a uniform bright background (e.g. [ 50 % full screen luminance)
3.1.6
partial subpixel defect subpixel or dot with part of the emission area obscured such that a visible difference in brightness is observed in comparison with neighbouring subpixels of the same colour
3.1.7
clustered subpixel defects subpixel or dot defects gathered in specified area or within a specified distance. Also known as “close subpixel defect” 3.1.8
unstable subpixel subpixel or dot that changes luminance in an uncontrollable way
3.1.9
pixel shrinkage reduction in the active emissive area of one or more subpixels (or dots) over time 3.1.10
panel edge shrinkage reduction in the active emissive area from the edges of the display area over time
3.1.11
line defect vertical or horizontal bright or dark line parallel to a row or column observed against a dark or bright background, respectively
3.1.12
bright line defect a line appearing bright on a screen displaying a uniform dark or grey pattern
3.1.13
dark line defect a line appearing dark when displayed with a uniform bright or grey pattern
3.1.14
mura region(s) of luminance and colour non-uniformity that generally vary more gradually than subpixel level defects. For classification, the maximum dimension should be less than one fourth of the display width or height SIST EN 62341-6-2:2012

– 8 – 62341-6-2 © IEC:2012 3.1.15
line mura variation in luminance consisting of one or more lines extending horizontally or vertically across all or a portion of the display (such as may be caused by TFT threshold voltage variation from laser induced crystallization)
3.1.16
colour mura
mura that appears primarily in only one colour channel and results in a local variation of the white point (or CCT)
3.1.17
spot mura
region of luminance variation larger than a single pixel appearing as a localized slightly darker or brighter region with a smoothly varying edge
3.1.18
stain mura
region of luminance variation larger than a single pixel appearing as clearly defined edge bordering a region of brighter or darker luminance than surrounding regions
3.1.19
mechanical defects image artefacts arising from defects in protective and contrast enhancement films, coatings, mechanical fixturing, or other elements within in the active area of the display
3.1.20
scratch defect
defect appearing as fine single or multiple lines or scratches, generally light in appearance on a dark background, and independent of display state 3.1.21
dent defect
localized spot generally white or grey in appearance on dark background and independent of display state
3.1.22
foreign material
defect caused by foreign material like dust or thread in between contrast enhancement films, protective films, or on emitting surface within the active area of the display
3.1.23
bubble defect caused by a cavity in or between sealing materials, adhesives, contrast enhancement films, protective films, or any other films within the visible area of the display
3.1.24
ambient contrast ratio contrast ratio of a display with external natural or artificial illumination incident onto its surface
NOTE Includes indoor illumination from luminaires, or outdoor daylight illumination. 3.1.25
colour gamut boundary surface determined by a colour gamut's extremes SIST EN 62341-6-2:2012

62341-6-2 © IEC:2012 – 9 – 3.1.26
colour gamut volume a single number for characterizing the colour response of a display device in a three-dimensional colour space
NOTE Typically the colour gamut volume is calculated in the CIELAB colour space.
3.1.27
ambient colour gamut volume number for characterizing the colour response of a display device, under a defined ambient illumination condition, in a three-dimensional colour space
NOTE Typically the colour gamut volume is calculated in the CIELAB colour space. 3.2 Abbreviations CCT correlated colour temperature CIE International Commission on Illumination (Commission internationale de l’éclairage) CIELAB CIE 1976 (L*a*b*) colour space DUT device under test HD
high definition ISO
International Organization for Standardization LED
light emitting diode LMD
light measuring device LTPS
low temperature polysilicon OLED
organic light emitting diode PL
photoluminescence QVGA
quarter video graphics array RGB
red, green, blue SDCM
standard deviation of colour matching sRGB
a standard RGB colour space as defined in IEC 61966-2-1 TFT thin film transistor TV
television UV
ultraviolet 4 Structure of measuring equipment The system diagrams and/or operating conditions of the measuring equipment shall comply with the structure specified in each item. 5 Standard measuring conditions 5.1 Standard measuring environmental conditions Electro-optical measurements and visual inspection shall be carried out under the standard environmental conditions, using at a temperature of 25 ºC ± 3 ºC, a relative humidity of 25 % to 85 %, and pressure of 86 kPa to 106 kPa. When different environmental conditions are used, they shall be noted in the visual inspection or ambient performance report. SIST EN 62341-6-2:2012

– 10 – 62341-6-2 © IEC:2012 5.2 Standard lighting conditions 5.2.1 Dark-room conditions The luminance contribution from the background illumination reflected off the test display shall be ≤ 0,01 cd/m2 or less than 1/20 the display’s black state luminance, whichever is lower. If these conditions are not satisfied, then background subtraction is required and it shall be noted in the ambient performance report. In addition, if the sensitivity of the LMD is inadequate to measure at these low levels, then the lower limit of the LMD shall be noted in the ambient performance report. NOTE Unless stated otherwise, the standard lighting conditions shall be the dark-room conditions. 5.2.2 Ambient illumination conditions 5.2.2.1 Ambient illumination conditions for visual inspection Ambient lighting conditions have a strong impact on the ability of the inspector to resolve defects and large variations of light intensity in the visual field can lead to inspector fatigue and a resulting loss of sensitivity to defects. Refer to ISO 9241-310 for general guidance on optimal illumination conditions for visual inspection of pixel defects [1]1. For inspector comfort and consistency of inspection conditions an average ambient illuminance of between 50 lx and 150 lx is suggested in the inspector’s work area. This ambient illuminance may be measured, for example, with an illuminance meter facing directly upward in a horizontal plane at the approximate eye level of the inspector. Care shall be taken to use diffuse illumination, and diffuse textures in the inspection environment, to avoid glare in the visual field of the inspector. As shown in Figure 1, the display under test shall be placed to avoid direct illumination from ambient room light sources. In addition, dark light-absorbing materials shall be used to cover specular surfaces that may be viewed by the inspector in direct reflection from the display surface. In any case, to limit degradation of the display contrast from ambient light, the ambient illuminance incident from room light sources on the display surface measured with the display off shall be < 20 lx. If ambient illuminance at the display surface is [ 20 lx, it shall be noted in the visual inspection report.
Diffuse light source No directional sources
Walls or room furnishings Dark, light- absorbing material Baffle or light shield Display device Inspector No directional sources IEC
84/12
Figure 1 – Example of visual inspection room setup
for control of ambient room lighting and reflections
————————— 1 Numbers in square brackets refer to the Bibliography. SIST EN 62341-6-2:2012

62341-6-2 © IEC:2012 – 11 – 5.2.2.2 Ambient illumination conditions for electro-optical measurements The following illumination conditions are prescribed for electro-optical measurements of displays in ambient indoor or outdoor illumination conditions. Ambient indoor room illumination, and outdoor illumination of clear sky daylight, on a display shall be approximated by the combination of two illumination geometries [2]. Uniform hemispherical diffuse illumination will be used to simulate the background lighting in a room, or the hemispherical skylight incident on the display, with sun occluded. A directed source in a dark room will simulate the effect of directional illumination on a display by a luminaire in a room, or from direct sunlight.
Some displays can emit photoluminescence (PL) when exposed to certain light. The relative impact of PL on the reflection measurement can be determined, and is described in Annex A. An illumination condition that causes a significant reflection measurement error due to the presence of PL should be treated carefully. If the same illumination spectral distribution and illumination/detection geometry is used for the reflection measurements, and the calculation of ambient contrast ratio and colour, then the PL can be incorporated into the reflection coefficients. However, if the illumination spectra used in the calculations is significantly different, then the reflected component must be measured separately from the PL component. The latter case is not addressed in this document.
The following illumination conditions shall be used to simulate indoor and outdoor display viewing environments:
Indoor room illumination conditions: • Uniform hemispherical diffuse illumination – Use a light source closely approximating CIE Standard Illuminant A, CIE Standard Illuminant D65, or fluorescent lamp FL1 as defined in CIE 15. The use of an infrared-blocking filter is also recommended to minimize sample heating from the illuminants. The UV region (< 380 nm) of all light sources shall be cut off. If FL1 is used as a light source, the chromaticity tolerance area of the lamp shall be less than 5 standard deviation of colour matching (SDCM, see IEC 60081). The fluorescent lamp shall be stabilized, for example, by ageing for 100 hours, and not used beyond 2 000 hours. Additional sources may also be used, depending on the intended application. For spectral measurements, if it can be demonstrated that the display does not exhibit significant PL (< 1 % PL, see Annex A) for the selected reference source spectra, then a spectrally smooth broadband source (such as an approximation to CIE Standard Illuminant A) may be used to measure the spectral reflectance factor. Without significant PL, a measurement of the spectral reflectance factor using a broad source (like Illuminant A) enables the ambient contrast ratio and colour to be calculated later for the desired reference spectra (for example D65). The indoor room contrast ratio shall be calculated using 60 lx of hemispherical diffuse illumination (with specular included) incident on the display surface for a typical TV viewing room, and 300 lx for an office environment [3]. The actual hemispherical diffuse reflectance factor measurement may require higher illumination levels for better measurement accuracy. The results are then scaled to the required illumination levels. • Directional illumination- The same source spectra shall be used as with hemispherical diffuse illumination. If a different spectral source is used, it shall be noted in the ambient performance report. The presence of significant PL (see Annex A) shall also be determined for the measured source, and the preceding limitations be applied when PL is present. The indoor room contrast ratio or colour shall be calculated using directional illumination of 40 lx incident on the display surface for a typical TV viewing room, and 200 lx for an office environment with the display in the vertical orientation. The actual reflectance factor measurement may require higher illumination levels for better measurement accuracy. The directed source shall be 35 ° above the surface normal (θs=35 °, θd=0 °, see Figure 3) and have an angular subtense of no more than 8 °. The angular subtense is defined as the full angle span of the light source from the centre of the display’s measurement area. SIST EN 62341-6-2:2012

– 12 – 62341-6-2 © IEC:2012 NOTE Other illumination levels may be used in addition to those defined above for calculating the ambient contrast ratio under indoor illumination conditions. However, approximately 60 % of the total illuminance should be hemispherical diffuse, and 40 % directional illumination. Daylight illumination conditions: • Uniform hemispherical diffuse illumination – Use a light source closely approximating skylight with the spectral distribution of CIE Illuminant D75 [4]. Additional CIE daylight illuminants) may also be used, depending on the intended application. An infrared-blocking filter is recommended to minimize sample heating. The UV region (< 380 nm) of the light source shall be cut off. For spectral measurements, if it can be demonstrated that the display does not exhibit significant PL for a 7 500 K correlated colour temperature (CCT) source, then spectral reflectance factor measurements can be made using a spectrally smooth broadband source (such as an approximation to CIE Standard Illuminant A). The contrast ratio or colour can be calculated later for the D75 Illuminant spectra. The daylight contrast ratio and colour shall be calculated using 15 000 lx of hemispherical diffuse illumination (with specular included) incident on a display surface in a vertical orientation [4,5]. The actual hemispherical diffuse reflectance factor measurement may be taken at lower illumination levels.
• Directional illumination – The directional light source shall approximate CIE daylight Illuminant D50) [4]. Additional CIE daylight illuminants may also be used, depending on the intended application. The use of an infrared-blocking filter is recommended to minimize sample heating. The UV region (< 380 nm) of the light source shall be cut off. If it can be demonstrated that the display does not exhibit significant PL for a source approximating Illuminant D50, then a spectrally smooth broadband source (such as an approximation to CIE Standard Illuminant A) may be used for the reflectance factor measurement. The ambient contrast ratio or colour can be calculated later with the D50 Illuminant spectra. The daylight contrast ratio or colour shall be calculated using 65 000 lx for a directed source at an inclination angle of θs = 45 ° to the display surface (see Figure 3) [4][,5]. The actual reflectance factor measurement may be taken at lower illumination levels, and the contrast ratio and colour calculated for the correct illuminance. The directed source shall have an angular subtense of approximately 0,5 °.
For daylight contrast ratio and colour calculations from spectral reflectance factor measurements, the relative spectral distributions of CIE Illuminant A, lamp FL1, D65, D50 and D75 tabulated in CIE 15 shall be used. Additional CIE daylight illuminants shall be determined using the appropriate eigenfunctions, as defined in publication CIE 15. 5.2.2.3 Uniform hemispherical diffuse illumination An integrating sphere, sampling sphere, or hemisphere shall be used to implement uniform hemispherical diffuse illumination conditions. Two possible examples of the measurement geometry are shown in Figure 2. If an integrating sphere that is at least seven times the physical outer diagonal of the display is available, the display can be mounted in the centre of the sphere (Figure 2, configuration A). For large displays, a sampling sphere (configuration B) or hemisphere would be more suitable. In all cases, the configuration shall follow the standard di/8 ° to di/10 ° illumination/detection geometry, where di is the standard notation for diffuse. SIST EN 62341-6-2:2012

62341-6-2 © IEC:2012 – 13 –
Configuration B (side view) Baffle Display 8°-10°
Reflectance standard Light measuring device Configuration A (top view) Display Lamp Measurement port θ = 8°-10° θ Display Lamp Baffle Sample port Light source Specular
Point θ IEC
85/12
Figure 2 – Example of measurement geometries for diffuse illumination condition
using an integrating sphere and sampling sphere
a) The display is placed in the centre of an integrating sphere/hemisphere, or against the sample port of a sampling sphere. The reflected luminance off the display from the sphere shall be much greater than the luminance from the display-generated light. For displays without significant PL, the reflected luminance from the sphere can be estimated with the display turned OFF.
b) For daylight measurements with an approximate 7 500 K CCT light source, an infrared-blocking filter is recommended to minimize sample heating. The colour temperature and illumination spectra can be measured from the reflected light of a white diffuse reflectance standard near the display measurement area (Figure 2, Configuration A), or the sampling sphere wall adjacent to the sample port (Figure 2, Configuration B.). The type of light source used, and its CCT, shall be noted in the ambient performance report. c) The light measuring device (LMD) is aligned to view the centre of the display through a measurement port in the sphere wall at an 8 ° (−0 °, +2 °) angle from the display normal. The required LMD angle of inclination can also be realised by tilting the display within the integrating sphere. The LMD is focused on the display surface. d) The measurement port diameter shall be 20 % to 30 % larger than the effective aperture of the LMD lens. Care needs to be taken to avoid any direct light from the sources, or any bright reflections off any surface (other than the screen itself), from hitting the lens of the LMD in order to minimise veiling glare contamination of the reflected luminance measurement. The LMD shall be moved back from the hole so that the bright walls of the sphere are not visible to the LMD. In addition, the sample port diameter will typically need to be larger than 25mm in order for the luminance meter’s or spectroradiometer’s field of view to be completely contained within the sample port. e) The measurement port shall be bevelled away from the lens. The small diameter of the bevel is toward the LMD, and the large diameter on the inside of the sphere. f) The spectral irradiance or illuminance on the display can be measured using a white diffuse reflectance standard with known hemispherical diffuse spectral reflectance factor R(λ), or the photopically-weighted (or luminous) hemispherical diffuse reflectance factor R. The white diffuse reflectance standard must be calibrated under uniform hemispherical diffuse illumination in an integrating sphere. When an integrating sphere (configuration A) or hemisphere is used, the white diffuse reflectance standard shall be placed on the display surface. If t is the thickness of the white diffuse reflectance standard, then it shall be placed on the surface a distance of 5*t to 7*t from the measurement area. The white reflectance standard can also be placed adjacent and in the same plane as the display if the sphere illumination is uniform over that distance. In the case of the sampling sphere, the spectral irradiance can be determined by a measurement of the interior sphere wall adjacent to the sample port.[6] The hemispherical diffuse spectral reflectance factor, or SIST EN 62341-6-2:2012

– 14 – 62341-6-2 © IEC:2012 the luminous hemispherical diffuse reflectance factor, of the interior sphere wall can be determined by comparing the spectral radiance (or luminance) of the wall with that of a calibrated white diffuse reflectance standard placed at the sample port
(i.e. Rwall= Rstd*(Lwall/Lstd). g) If a sampling sphere is used, the display measurement area shall contain more than 500 display pixels. It is recommended that the sampling sphere be at least six times larger than the sample port diameter. If there is a significant distance between the display emitting surface and the sample port entrance, then the size of the sample port may need to be increased [7]. h) The illuminance across the display measurement area shall vary less than ± 5 % from the average. 5.2.2.4 Directed source illumination Directional illumination shall be simulated by an isolated directed source (Figure 3) at a defined angle of inclination to the display surface normal, or ring light (Figure 4) centred about the normal. This measurement shall be performed in a dark room, with all potential reflective room surfaces having a matt black coating. Light from the isolated directed source that is reflected off the display in the specular direction can be collected by a light trap to minimize its contribution to stray light contamination. The isolated directed source is the preferred directed source. If the display exhibits strong asymmetric scatter (matrix scatter [8]), then a ring light shall be used. a) Position the LMD normal (θd = 0 °) to the display, and focus on the display surface. The isolated directed light source is aligned in the same vertical plane (φs = 0 °) as the display normal and LMD, but at an inclination angle θs from the horizontal plane. The distance between the display and directed source Cs can be adjusted so that the light source has an angular subtense of ≤ 8 ° for indoor applications, or approximately 0,5 ° angular subtense from the center of the display measurement area for outdoor applications. For ring light sources, a fibre-optic ring light shall be used, with an emitter angular subtense of approximately 0,5 °. The ring light emitting plane must be co-planar with the display surface and centred about the measurement area. The inclination of the light θs can be set by adjusting the ring light working distance to the display. The central clear aperture of the ring light shall be at least 30 % larger than the effective aperture of the LMD lens. Additional source/detector geometries can be used, but shall be noted in the ambient performance report.
b) The reflected luminance off the display from the directed source shall be much greater ([ 10) than the luminance from the display-generated light.
c) The spectral irradiance or illuminance at the display measurement position can be determined by a white diffuse reflectance standard with a known spectral reflectance factor or photopically weighted (or luminous) reflectance factor. The white diffuse reflectance standard shall be placed at the same measurement position as the display, which may require the display to be moved away for the measurement of the white diffuse
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